WASHINGTON, U.S. - After the U.S. President Donald Trump announced that the U.S. will recognize Jerusalem as Israel’s capital, several groups and world leaders expressed regrets.

On Wednesday, Trump reversed decades of U.S. policy and recognized Jerusalem as the capital of Israel in defiance of warnings from around the world that the gesture risks creating further unrest in the Middle East.

Delivering the crucial speech at the White House, Trump said his administration would begin a process of moving the U.S. embassy in Tel Aviv to Jerusalem, which is expected to take years.

Jerusalem, which is home to sites holy to the Muslim, Jewish and Christian religions, is one of the thorniest obstacles to reaching a peace deal between Israel and the Palestinians.

Trump said on Wednesday, "I have determined that it is time to officially recognize Jerusalem as the capital of Israel. While previous presidents have made this a major campaign promise, they failed to deliver. Today, I am delivering."

Israel considers Jerusalem its eternal and indivisible capital and wants all embassies based there.

However, Palestinians want the capital of an independent Palestinian state to be in the city's eastern sector, which Israel captured in a 1967 war and annexed in a move never recognized internationally.

Trump argued that his move is not intended to tip the scale in favour of Israel - adding that any deal involving the future of Jerusalem would have to be negotiated by the parties.

He said he remained committed to the two-state solution between the Israelis and Palestinians if they parties want one.

The president called on the region to take his message calmly and with moderation amid warnings of potential unrest in the Middle East.

Trump said, “There will of course be disagreement and dissent regarding this announcement—but we are confident that ultimately, as we work through these disagreements, we will arrive at a place of greater understanding and cooperation.”

Trump added that his move reflected the reality of Jerusalem as the centre of Jewish faith and the fact that the city is the seat of the Israeli government.

Following the announcement, Israeli Prime Minister Benjamin Netanyahu hailed Trump’s announcement as a “historic landmark" and urged other countries also to move their embassies in Israel to Jerusalem.

He added that any peace deal with Palestinians must include Jerusalem as Israel’s capital.

In response to the move, the Palestinians have said Trump's move would mean the "kiss of death" to the two-state solution, envisaging a Palestinian state in territory - the Gaza Strip, the West Bank and East Jerusalem - that Israel took in 1967.

Washington's allies in the region warned of dangerous repercussions ahead of Trump's announcement.

Even the Trump administration’s closest allies in the Arab world strongly condemned his embassy decision.

World leaders warned that Trump may have doomed the peace process and called for calm in the wake of violent threats from the Arab world.

EU foreign policy chief Federica Mogherini said, “The EU calls on all actors on the ground and in the wider region to show calm and restraint in order to prevent any escalation.”

She said that the EU is concerned about the “repercussions this may have on the prospect of peace.”

UN Secretary-General Antonio Guterres also expressed concern in New York and said, “I have consistently spoken out against any unilateral measures that would jeopardize the prospect of peace for Israelis and Palestinians. I understand the deep attachment that Jerusalem holds in the hearts of so many people. It has been so for centuries and it will always be. In this moment of great anxiety, I want to make it clear : there is no alternative to the two-state solution. There is no Plan B.”

UN Special Representative to the Middle East Peace Process Nickolay Mladenov said, “We all have to be very careful with the actions that we take.”

Meanwhile, France’s president, Emmanuel Macron, also called the decision “regrettable.”

Macron said the status of Jerusalem was not for one country to decide, but a matter of international security, of consensus and of law.

Egypt said it refused to recognize it and warned of grave consequences.

Turkey meanwhile threatened to sever ties to Israel, and the State Department’s office for embassy security warned of planned protests in all of its major cities.

Pope Francis called for Jerusalem's status quo to be respected.

He said that new tensions would further inflame world conflicts.

Speaking in the Vatican, Pope Francis said, “I wish to make a heartfelt appeal to ensure that everyone is committed to respecting the status quo of the city, in accordance with the relevant Resolutions of the United Nations. Jerusalem is a unique city, sacred to Jews, Christians and Muslims, where the Holy Places for the respective religions are venerated, and it has a special vocation to peace.”

He added the he prayed “that wisdom and prudence prevail, to avoid adding new elements of tension in a world already shaken and scarred by many cruel conflicts.”

China and Russia expressed concern that the plans could aggravate Middle East hostilities.

Meanwhile, British Prime Minister Theresa May spoke against the decision at the parliament and Labour Party leader Jeremy Corbyn attacked the move on Twitter as “a reckless threat to peace.”

A spokesman for May said, “We disagree with the U.S. decision to move its embassy to Jerusalem and recognize Jerusalem as the Israeli capital before a final status agreement. We believe it is unhelpful in terms of prospects for peace in the region."

However, U.S. special envoy Jason Greenblatt tweeted in support of Trump stating, “No matter how certain parties react, we will continue to be hard at work putting together our peace plan to benefit all parties.”

The largest mainstream and right-leaning Jewish groups too welcomed Trump’s announcement that the U.S. will recognize Jerusalem as Israel’s capital, while groups on the left expressed regrets.

Moments after Trump’s speech on Wednesday, the American Israel Public Affairs Committee tweeted, “Today’s action by @POTUS is an important, historic step for which we are grateful. We urge the president to quickly relocate our embassy to Israel’s capital.”

The Reform Jewish movement, the largest in the U.S., called Wednesday’s announcement “ill-timed but expected.”

The Union for Reform Judaism President Rabbi Rick Jacobs said on behalf of the organizations of the movement that the announcement, “affirms what the Reform Jewish movement has long held: that Jerusalem is the eternal capital of the Jewish people and the State of Israel. Yet while we share the President’s belief that the U.S. Embassy should, at the right time, be moved from Tel Aviv to Jerusalem, we cannot support his decision to begin preparing that move now, absent a comprehensive plan for a peace process.”

Jacobs added that the White House should not undermine efforts toward making peace between Israel and the Palestinians by “making unilateral decisions that are all but certain to exacerbate the conflict.”

Meanwhile, Malcolm Hoenlein, president of the Conference of Presidents of Major American Jewish Organizations, said Trump was doing “the right thing.”

Hoenlein said in an address at the launching of the Lobby for the Protection of the Mount of Olives in the Knesset, “When President Trump visited the Western Wall and made a declaration recognizing Jerusalem as holy to the Jews after the denunciation of UNESCO, there was not even one warm-up, not one demonstration, because when you do the right thing, you do not have to ask questions, you just do it.”

And the Anti-Defamation League called the step “important and long overdue,” but urged all parties “to work together to reduce tensions and create conditions conducive for the rapid resumption of Israeli-Palestinian negotiations leading to a two-state solution.”

AIPAC added that it has long supported an “undivided #Jerusalem” as the “historic, current and future capital of Israel.”

AIPAC tweeted, “Relocating the embassy to #Jerusalem does not in any way prejudge the outcome of the Israeli-Palestinian #peace process, to include establishing two states for two peoples and resolving Palestinian claims to the eastern portion of the city and the disposition of holy places.”

The American Jewish Committee, Hadassah and the Jewish Federations of North American also welcomed the president’s announcement without reservations.

The Republican Jewish Coalition praised the president for his announcement of a “significant change in U.S. policy” by recognizing Jerusalem as Israel’s capital and announcing a plan to begin the process of moving the U.S. Embassy to Jerusalem from Tel Aviv.

Norm Coleman, the RJC’s national chairman and a former Minnesota senator, said in a statement, “President Trump is doing what he does so well: recognizing the reality on the ground. No more false news — Jerusalem is Israel’s capital.”

Mort Klein, head of the Zionist Organization of America said, “I am pleased that after 22 long years since the embassy bill passed that Trump is going to be finally recognizing the obvious. I am disappointed that he is signing a waiver two days after the deadline. I would have preferred he take the existing consulate or another government-owned building, put a sign on it and say this is the embassy, immediately.”

And the Simon Wiesenthal Center said that with his announcement, Trump “will right a historic wrong.”

Further, Rabbi Yechiel Eckstein, founder and president of the International Fellowship of Christians and Jews, called the announcement “a bold, courageous move that is long overdue, and is especially significant coming from Israel’s closest ally. Both Jews and Christians around the world have prayed for this day, which rights a historic wrong by affirming to the world that Jerusalem is the eternal capital of the Jewish people.”